A person buys a phone for 84 and signs up for a singleline p

A person buys a phone for $84 and signs up for a single-line phone plan with 2000 monthly anytime minutes. The plan costs $116.93 per month. Write an equation that can be used to determine the total cost, C(t), of this phone plan for t months. Then, find the cost for 21 months, assuming that the number of minutes the person uses does not exceed 2000 per month.

Solution

Total cost = phone cost + (monthly plan cost)(Number of months)

==> C(t) = 84 + (116.93)(t)

==> C(t) = 116.93t + 84

t = 21 ==> C(21) = 116.93(21) + 84

==> C(21) = 2539.5

Hence cost for 21 monts = $2539.5